Growing of cotton uses a lot of valuable water, unless organic masses of biocides and even when fairtrade mostly exploits the relatively poor.

. . . the whole cotton industry is one of the most toxic industries on the planet! (In the top 5). The cultivation of cotton requires enormous quantities of toxic chemicals, in the form of pesticides, herbicides, fungicides and fertilizers. This cotton is sourced from India, so . . . the soil, air, water and people in India are being polluted. Not only that, the finished canvas is then imported to . . .
sagebrush tipi works

Flax could be fitted in well with small-scale farming and indeed as a crop was considered as providing useful employment for labourers during quieter periods in the farming year[16]. It was a labour intensive crop, well-illustrated by the estimate that 1 acre of flax needed 82 man days for weeding, far more than other crops, such as rye needing the least at 21 days[17]. It also depleted the soil with 19thC writers recommending it ought not to be grown in the same soil more than once every 10 years[18].
. . . The widely accepted yield of 50 stones (sts) of usable fibres per acre of flax[9] . . .
jennidobson

50st > 700lb > 700yds2 (585m2) of 16oz canvas > 778m2 of 12oz
700lb = 318Kg so I'd need to efficiently grow approx 490sq yds to get 32kg (22 x 22)yds (20 x 20)m2

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Write-up on hemp to come? Maybe!